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This is the inside of the tank on my cb400a it’s full of little rust spots all over but they don’t seem bad. Do I need to treat this at all?
E5140D03-E203-4FD6-B338-58CEFCB7CF54.jpeg
 

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There's not much you can do about rust forming in a steel fuel tank. If you coat the inside with that rubber stuff like some people try to do, we can read about how the next guy tries to remove that stuff next year.
 

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Secret Agent
2006 Honda CBR1000RR, 2008 Honda CRF230L, 2019 Honda CRF1000L
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I wouldn't worry bout the little bit, just keep gas in it, especially over winter, keep it full then.
 

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Short Fuse
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The rust is probably because the UK (and many other countries) fuel has added Ethanol. Ethanol is hygroscopic - meaning that it attracts moisture. Moisture (water) causes rust.

Maybe look at using a fuel additive such as Seafoam or any other rust preventative fuel additive.
 

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This is the inside of the tank on my cb400a it’s full of little rust spots all over but they don’t seem bad. Do I need to treat this at all? View attachment 68907
That isn't bad at all however I would put a fuel tank liner in it before it gets any worse. I use Red Kote. It's like pouring a quart of paint inside the tank and you tip it at all angles to get 100% coverage and then pour out what is left and allow to dry. The liner will list more than 10 years.
 

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then what happens to it?
Not really sure. I have a Jeep that had pin hole leaks and I lined the tank with it ten or twelve years ago and it's still in good condition. My guess when it starts failing it would have spots here and there gas would get under it.
 

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Not really sure. I have a Jeep that had pin hole leaks and I lined the tank with it ten or twelve years ago and it's still in good condition. My guess when it starts failing it would have spots here and there gas would get under it.
Actually it starts to degrade, disintegrate and try to travel into your engine if the fuel filter doesn't catch it all.
I would recommend it just as soon as they start selling redcoat remover that works equally well.

... might want to check that jeep fuel filter for any red stuff.
 

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Actually it starts to degrade, disintegrate and try to travel into your engine if the fuel filter doesn't catch it all.
I would recommend it just as soon as they start selling redcoat remover that works equally well.

... might want to check that jeep fuel filter for any red stuff.
I only use the clear filters and there hasn't been anything in them unusual.
 

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Short Fuse
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Personally I would not use Red Kote in a motorcycle tank. Here is an excerpt from the company's own specification sheet:

68923


Not sure that I would want to risk my paint with this product.
 

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This is the inside of the tank on my cb400a it’s full of little rust spots all over but they don’t seem bad. Do I need to treat this at all? View attachment 68907

seal the openings up and drop a porch swing chain in there (about 3 ft, it has twisted links with points) and about a half a cup of baking soda.... half cup water. put the cap on and shake the shyt out of it, let it sit for a few, repeat two to three time over a few hours.
Drain, flush with water, drain again, and add some of fuel. repeat the shaking around. do this step 3 times, so fuel washes out the water. remove the chain and flush with fuel again if desired, install shutoff valve and fill up using seafoam every time for the rest of the season, and you will be good to go. PS: its a waste of fuel, but if you store a tank like this full of fuel, it will not rust any further, as no oxygen can get to the rust spots. and install a "Glass" fuel filter that can be disasembled and cleaned out if necessary...:)

moisture alone does not cause rust, it has to have oxygen also...
 

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Bürgerpolizei
2009 Ninja 500r
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Never ever used any coating on my tanks but have used fuel stabilizers and transmission fluid and seafoam. Jury is still out on seafoam even almost 20 years later.
 

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Your jeep has a clear fuel filter? Isn't there one inside the fuel tank before the fuel pump?
Fuel injected or carb jeep?
There isn't a fuel filter in either of the tanks. It's a 1975 CJ5 with a carburetor. The fuel pump is on the engine. It has a 15 gallon tank under the back end and a 10 gallon tank under the drivers seat.

All I can say about the paint on the tanks is one tank was new with what ever paint they use and I put the liner in it before installing it. While it didn't have the same paint job you would have on a motorcycle it didn't affect the paint at all. I even spilled some on the exterior and I just wiped it off. The other tank I painted with an acrylic enamel base coat and topcoated it with a urethane clear coat. I didn't have an issue with the paint on it either. If the urethane clear coat can hold up to the gas they make today I can't picture Red Kote lifting it.
 

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Most recent issue with liquid tank liner I heard was from a motorcycle mechanic friend attempting to remove the white rubber like liner from a Bultaco fuel tank, he found bits of white material throughout the fuel system. But that is a gravity feed tank and the bits are heavier then the fuel. If your jeep tank has bits of liner in it they will be on the bottom of your tank, not as likely to be sucked up by a fuel pickup that surely at the very least has a screen on the intake end or is elevated from the lowest spot in the tank.

Next question would be, what are the dissolved chemicals in decomposing rubber tank liner going to do to your piston and rings when they eventually burn up in the combustion chamber?
 

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I just don't see any evidence of the liner decomposing. I've had both gas tanks out in the last few years replacing the sending units and there wasn't anything in the gas. If it is decomposing it's completely liquefying the liner. There isn't anything white on the surface, it's still red like it was when I applied it. In my case I had actual leaks in the tank under the seat. I think if it's going bad the tank would be leaking again.
 

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... the white tank liner material is a similar product from a different maker. I've only heard bad experiences from either one, because it was usually from somebody trying to remove the old stuff from a leaking tank or after their carburetor plugged.

If the rubber stuff was any good then why are all steel fuel tanks not lined with it straight from the manufacturer.

I hope you are right and the stuff is a miracle cure for your jeep, but I don't put anything into my fuel tank that I don't intentionally want to go into my engine.
 

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I dont believe in the use of "tank liners" its eith a tank I will use and weld up, or if too rusted, cut out the rust and patch it. If its too much to be able to patch, then its a throw away for me..
 

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A bladder would make way more sense, that's what they do in airplanes and you can even replace it occasionally.
 

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Maybe the problem is with the other brand. Red Kote was recommended to me and that is all I have experience with. It may also be how I prepared the tank. I thoroughly cleaned the tank with solvents and then put a bunch of nuts and bolts in the tank and carried the tank around in the back of my truck for several days and then cleaned it again.
 
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